I keep reading about the lag issues etc with the 13" 2015 MBP. I currently have the 27"retina fully loaded iMac but after being tied down all day at work with a desktop Im starting to prefer the portability of the 13" MBP. Im considering selling the retina iMac. I just don't want to sit at a desk when I am at home. I picked up the middle road 13" MBP at the apple store and have no issues.